Download Youtube video is easy....

How to save/download video
from youtube ?

Why you should download/save videos from youtube
:

You found an interesting video from youtube and you
want to save/download it to your computer and later share it with your friend or
keep it as a collection. However, by default Youtube doesn't allow users to
save/download the videos. It only allow user to send a hyperlink to the friends
and invite them to go to youtube website to view the videos.

It will become a problem because these video may gone
forever due to copyright infringement issues, why not save/download the video
before it's too late ?